Median: The median response time (50th percentile) of HTTP requests within the specified sampling interval (10 or 1 minute). This means that 50% of an application’s web requests were completed within less time than the median, and 50% were completed within more.

95th Percentile: The 95th percentile response time of HTTP requests within the specified sampling interval. This means that 95% of an application’s web requests were completed within less time, and 5% were completed within more. This is helpful for providing an upper bound (but not maximum) for expected response times.

Response Throughput

OK: The number of successful (status codes < 500) requests serviced per minute. For a 10 minute rollup, this is the total number of successful requests divided by 10 to provide per-minute values.

Failed: The number of failed (status codes >= 500) requests serviced per minute. For a 10 minute rollup, this is the total number of failed requests divided by 10 to provide per-minute values.

RSS: The amount of memory (megabytes) held in RAM across dynos of a given process type. Max RSS is reported for each 10 or 1 minute interval.

Swap: The portion of a dyno’s memory, in megabytes, stored on disk. It’s normal for an app to use a few megabytes of swap per dyno. Higher levels of swap usage though may indicate too much memory usage when compared to the dyno size. This can lead to slow response times and should be avoided. Max swap is reported for each 10 or 1 minute interval.

Total Memory: Mean total memory represents the portion of memory which user’s can optimize and is shown as the sum of rss and swap as measured in 10 or 1 minute increments and averaged across all dynos.